1. Field of the Invention
Embodiments of the invention relate electronic percussion instruments and vibration detection apparatuses. More particularly, embodiments of the invention relate to electronic percussion instruments and vibration detection apparatuses having a simplified frame structure with a highly uniform sensitivity distribution.
2. Related Technology
Electronic percussion instruments such as electronic drums have sensors for detecting vibrations caused by striking of the drum. Electronic drums may be configured to control a musical tone in response to detected striking.
Acoustic drums may be struck in several different manners to produce different sounds. A conventional drum sound is produced by striking the drumhead. Another type of sound, referred to as a rim shot, is produced by striking the rim of the drum. Two types of rim shots are possible. In an open rim shot, the rim and the drumhead are struck simultaneously, producing a characteristic drum overtone effect. In a closed rim shot only the rim is struck, producing a clattering percussive sound.
A goal of electronic percussion instruments has been to enable both conventional head strikes and rim shots. Japanese Unexamined Patent Application Publication (Kokai) Number Hei 10-20854, which corresponds to U.S. Pat. No. 5,920,026, discloses an electronic drum that is furnished with a head arranged on a hollow body section. A first sensor detects vibrations produced by striking of the head, and a second sensor detects vibrations produced by striking of the rim. The signals from these two sensors make it possible to reproduce both types of rim shots.
A structure for attaching head and rim sensors to an electronic drum is disclosed in Japanese Unexamined Patent Application Publication (Kokai) Number Hei 10-198375. In this structure, a sensor frame having an approximately U-shaped cross section is arranged inside a hollow drum body to extend between the sides of the drum body. A rim shot sensor is arranged at the center of the drum at a lower portion of the frame. The location of the rim shot sensor at the center of the drum allows vibrations transmitted from the drum body to the rim shot sensor through the sensor frame to be detected with reasonable certainty. A head sensor is also arranged at the center of the drum on the sensor frame. The head sensor is arranged on a vibration isolating damper in direct contact with the head, allowing head strikes to be detected while rim shot strikes are suppressed.
The aforementioned structure is complicated in that the sensor frame is provided as a single elongated member that is affixed at its ends to the inside of the body section using screws. Fabrication is therefore complicated by the need to form holes in the drum body for attaching the sensor frame, and the number of parts needed to form the attachment.
In addition, because the sensor frame is provided as a single elongated structure, the sensor frame only makes contact with the drum body at two opposing points at its periphery, and so the quality of the vibrations that are transmitted from the rim through the sensor frame to the rim shot sensor changes depending on the location of the rim strike. Consequently, the rim shot strike sensitivity distribution of the drum is uneven, causing an impairment of performance characteristics.